1. Field of the Invention
Broadly conceived, the present invention relates to syringes. More particularly, the present invention relates to a syringe mixing apparatus wherein a plurality of substances can be first mixed together and then expelled all from a single delivery tip.
2. The Prior Art
In the field of dentistry, there are many types of procedures that require the mixing of two or more substances before the mixed compound can be used in a particular dental procedure. A common practice in the dental arts is to measure the separate substances drop-wise into a well or mixing dish and to then mix the separate substances together using an applicator brush, which in turn is then used to apply the mixed compound to the desired teeth surfaces. As will be appreciated, in dentistry it is often necessary to mix relatively small amounts because of the small surface areas that are to be worked upon. Furthermore, the materials which are mixed are often expensive and therefore, rather than mix larger quantities, relatively small quantities are mixed repeatedly so as not to waste undue amounts of the materials in question. Repeated mixing, of course, becomes tedious and time consuming.
The described procedure also suffers from other disadvantages. For example, when mixing separate substances in a well or mixing dish with an applicator brush, the applicator brush must be moved from the mixing well into the patient's mouth for purposes of applying the mixed substance to the tooth surfaces, then back to the mixing well to obtain fresh quantities of the mixed substance and then back to the patient's mouth again. This type of back and forth motion between the patient's mouth and mixing well means that each time the brush is removed from the patient's mouth, the applicator brush must be repositioned with the tooth surface when it is inserted back into the patient's mouth. Furthermore, there is added risk of inadvertently touching the lips, gums, or other parts of the mouth by virtue of having to reposition the applicator brush with the tooth surface each time the brush is removed back to the mixing well to obtain fresh quantities of the mixed substance on the brush applicator. Not only does this create the possibility of irritating the patient's lips, gums, or other tissue, but it also creates the possibility of contaminating the mixed substance with saliva, so as to change the composition of the mixed substance in an undesirable way.
Further problems with the described procedure arise in connection with the potential bacterial contamination to the mixing well or dish by repeated moving of the applicator brush from the patient's mouth to the mixing well. This creates the need to sterilize the mixing well, which adds additional expense and time to office procedures, as well as creating potential risk for contamination of other patients if the mixing well is not properly sterilized between patients. Alternatively, if the mixing well is made of materials so as to be disposable, this adds an increased burden on the environment since typically such materials are made of plastics.
Still other problems in connection with the described procedure may arise where the substances that are mixed are of a relatively low viscosity. In order to obtain a sufficient quantity of the material when using an applicator brush, the brush tip typically has to be made somewhat larger so that the required quantities of materials can be carried to the mouth. However, the larger size applicator brush makes precise placement and working of the materials more difficult and thus results in a less precise delivery of the materials to the desired tooth surfaces.
Yet a further problem is that even once the substances are mixed in the mixing well, for some types of substances evaporation can become a problem. For example, it is common to mix hydrophilic resins in acetone for use in certain types of bonding procedures used in dentistry. The acetone can evaporate rapidly if it is left sitting very long in a mixing well, and this can adversely change the concentration of the mixed substance so as to change the bonding characteristics of the mixed substance. This further complicates the procedure and may require repeated mixing rather than using larger quantities of the mixed substance. As will be appreciated, this, of course, also adds to the tedium, expense and the difficulty of the overall procedure.